By clicking Tools > Options > Privacy> View
You can see who has you on their list. Using this list, and your own, you can see who is on your list that doesn't have you on their's, and vice versa, but a script to do this, would be quite nice. (allowing you to add,delete,block, unblock said persons from there)

This feature is already supported by Messenger Plus!
You can see this in Contact Info and the actions you've requested are already in the Contact Manager

I think he means "People that you have but they dont have you" and a "People that have you, but you dont".

Right now its just a large list of the people who have you, and the people who you have.

Yeah, that's exactly what i mean, mattisdada.
It's somewhat of a mouthful, and i was having trouble trying to phrase it so it could be understood easily.

Edit: Had a look. It looks to me like it already has everything i was asking for. Thanks.

Edit2: Actually what i can see this is missing. (about all it is actually)
Is the option to view msn profiles of said contacts.

(and well being able to tell if they've blocked you..but that would probably require cooperation with microsoft so you knew what sort of response the server was really giving to sending the data packet or w/e.)
It's actually a shame that any script to say if someone has blocked you etc is so unreliable. [/offtopic]

bump